Electrical switch mechanism



March 20, 1956 R wE|DE 2,739,192

ELECTRICAL SWITCH MECHANISM Filed Aug. 18, 1952 2 Sheets-Sheet lInventor By @7 Attorneys March 20, 1956 c w m 2,739,192

ELECTRICAL SWITCH MECHANISM 2 sneels shee'. 2

Filed Aug. 18, 1952 Inventor Attorneys United States Patent ELECTRECALSWETCH MECEANISM Rudolph C. Weitle, La Grange, Ill.,-assignor to GeneralMotors Corporation, Detroit, Mich corporation of Delaware ApplicationAugust 18, 1%52, Serial 395,617 8 Claims. (Cl. see-s This inventionrelates generally to electrical switch mechanisms and more particularlyto electrical switch mechanisms used in conjunction with the camswitches on electrically powered vehicles equipped with dynamicb'raking. The invention will be described in connection with the camswitches used on diesel electric locomotives. It should be understood,however, as the description proceeds that the invention is not limitedto electro-mo'tive power only but has a much wider field of application.

in the diesel electric field it is well known that a main generator isdriven by a diesel engine to supply electrical current to a plurality oftraction motors geared to axles that turn the driving wheels or" alocomotive. It is also well known that dynamic braking may beaccomplished on these locomotives by means of a cam switch which whenthrown simultaneously connects the traction motor across dynamic brakingresistor grids.

The cam switch generally constitutes a pneumatically operated rotarymultiple pole switch provided with terminals with which the maingenerator, the fields of the traction motors and the armatures of thetraction motors are directly or indirectly connected. Also forming apartof the cam switch are sets of stationary contacts for each tract-ionmotor which may be connected in power or in brakingby means of themovable contacts on the rotating portion.

In multiple pole switches such as the cam switch described above, thereoften arrive occasions when it is desirable to prevent the completion ofonly one of the several circuits normally closed by such a switch. Forexampi'e, if a traction motor on a locomotive should become defectiveand no longer be capable of supplying motive power, it would become mosturgent to isolate such a motor from the power circuit connecting themain generator and the traction motors together or its dynamic brakingcir" it to prevent the possibility of short cir'cuiting and to relievethe resulting drag on the other traction motors. When a traction motoris isolated, however, themain ig'en- 'e'rat'or when connected in powermay become overloaded and therefore it becomes necessary to provideswitching means used in combination with an additional circuit tocorrect or prevent such overloading.

It therefore becomes an object of this invention to provide a switchingmechanism to be used in combination with 'a multiple pole switch and thecircuits normally closed by the multiple pole switch which will preventthe comple'tion of one of said circuits when said multiple pole switchisclosed.

It is a iurtl'ier object of this invention to provide a switching meansto be used in combination with a multiple 'pol'e switch and the circuitsnormally closed by the r'nultipl'e pole switch, which will prevent thecompletion of one of said circuits and at the same time o erate anadditional circuit adapted to compensate for certain changes which musttake place when said normally closed circuit is not "completed.

It is a further object of this invention to provide oh an electricallypowered locomotive the novel combination of 2,7393% Patented Mar. 20,1956 a cam switch used to place the traction motors of the lecomotiveacross dynamic braking grids and a manually accessible motor cut-outswitch on each pole compartment of the cam switch which when operatedserves to isolate a traction motor from the power circuit or dynamicbraking circuit of the locomotive.

It is a further object of this invention to provide mechanism forsetting up a special low voltage control system which takes care of thenecessary changes in the heavy current power or braking circuits afterone or more traction motors have been disconnected.

It is a further object of this invention to provide a mo tor cut-outswitch for the cam switch of a locomotive which is simple andinexpensive to manufacture and will readily adapt itself to equipmentcurrently in use.

In the drawings:

Figure l is a top view of one set of stationary contacts of a cam switchshowing the new movable contacts attached to one rotary portion of theswitch with the means for retracting the movable contacts.

Figure 2 is a front view taken on the line 2-2 of Figure 1, andillustrates the cam means for retracting the movable contacts.

Figure 3 is a side view taken along line 3-3 of Figure -l, to show theactuation means for the low voltage control switch.

Figure '4 is a modification of the switch shown in Figure 1.

Figure 5 is a front view of the modification taken along the line ii-15and serves to more clearly illustrate the modified cam means.

Figure 6 is a fragmentary side view taken along the line 66 of Figure 4and shows the camming mechanism in an intermediate position.

Referring now to Figures 1, 2 and 3 one pair of oppositely disposedstationary contact carriers 2 for the can switch of a locomotive areshown. These carriers '2 are fastened to vertical insulated members 4 bymeans of brackets '6 and bolts 8. Secured to the contact carriers 2 bybolts 10 are a pair of contact tips 12. interposed between the contacttips 12 and fastened to a rotatable portion 14 of the cam switch by abolt 18 and a washer 20 is a contact carrier 16.

Attached to the top of the contact carrier 16 and insulated therefrom bymeans of a tefion pad 22 is a low voltage control switch 24 ofconventional design. The low voltage control switch 24 is secured bymeans of insulated studs 26 and screws Conductors 29 are shown connectedto the low voltage switch 24 by the screws 30. l hese conductors 29'connect switch 24 with various wellknown low voltage circuits which itis adapted to control. Also shown fastened to the contact carrier 16 bymeans of screws 34 is a bracket 32. The bracket 32 has a grommet36p1'o'vided in a bent portion 38 which supports the conductors 29.

A pair of contact members oppositely disposed with respect "to thecontact carrier 36 are pivotally attached to the rotatable member 14 andthe bracket 32 by means of pins 42, 44 and slots 45, 43 respectively.The bracket 32 and a second bracket 5t"? also serve as retaining meansfor the pivoted ends of the contact means 49. interposed between thecontact members 40 and the contact carrier 16 are a pair of helicalsprings 52 seated in recesses in the members 48 and the carrier 16. Amanually operated cam member 5 3 having a pair of curved slots 56 isrotatably fastened to the carrier 16 by the same bolt 18 and washer 26'that attach carrier 16 to member 14. Adapted to ride in the slots 56 andalso in a pair of guide slots 58 provided in one end of the carrier 16are two pins 60. The pins 68 are securely fastened to the contactmember's'40 by means of threads on the pins and threaded holes in thecontact members 40.

Attached to one side of the carrier 16 by means of screws 65 and adaptedto actuate a button 66 of the low voltage switch 2% is a springactuating lever 63. Also provided on each of the contact means 40 areunique arc protective contacts 62 adapted to engage mating areprotective contacts 64 fastened to the stationary contacts 12.

The operation of the cam switch including the retracting means for themovable contacts 4i? is as follows: 1

The rotatable member 14 is shifted back and forth by suitable drivingmechanism for the entire cam 7 switch. When this driving mechanism movesthe rotatable member 14, the contact carrier 16 and the contactmeans'40into "the position shown in Figures 1, 2 and 3, the spring 52urges the contact member 49 tightly against the stationary contact 12and also against the rotating portion '14. Before the stationary contact12 and the movable contact means 40 engage each other,however,'thearcprotective means 64 and 62 make contact to prevent anyarcing and subsequent burning of the contact 12 and contact members 40.A certain amount of give is provided forcoutact -members 40 because ofthe slots 46 and Sit-which allow the pins 69 to slide back against theaction of the springs 52. In other words, the firmness of the contactwhich is made between contacts 12 and 40 and the rotatable mem- .ber14.is almost wholely determined by the characteristics of the helicalspring 52.

If, now, for some reason it shouldbe desirable to prevent. thecompletion of a circuit through the rotatable member 14, the movablecontact members 40 and one of the stationary contacts 12 when therotatable member is in the position shown, the cam means 54 may beactuated or rotated in a clockwise direction. This rotation .of the cammeans 54 causes the pins 69 to be directed inward toward the contactcatrier l6 and along the slots 58 by means of the slots 56. Suchmovement of the pins 60 causes the contact members 4% also to bedirected toward the contact carrier 16 and moves them out of engagementwith the stationary contacts 12. When the contact mem ber 40 shown tothe left of the carrier 16 is moved toward the contact carrier 16 andaway from the stationary contact 12, its inner portion engages thespring lever 68 which in turn presses against a button 66 on the lowvoltage con trol switch 24 to change the connections of the conductors29 fastened to the low voltage control switch 24.

Referring now to Figures 4, 5 and 6 a modification of the switch shownin the first three figures will be described. The same stationarycontacts 12 are shown oppositely disposed and mounted in a similarmanner to those in'Figure l. Themeans, however, attached to one of therotatable portions 14 of the cam switch differ in certain respects. InFigures 4, 5 and 6 a contact carrier member 70 is shown attached to therotatable portion14 by means of a bolt 72 and a washer 74. Pivotallyattached to the carrier 70 by means of pins 75 are two contact members76 each hav ing a contact tip 73 suitably fastened thereto. Joining eachcontact member 76 and contact tips 78 with the rotatable portion 1-4 isa woven, laminated. flexible conductor 89. These conductors 80 aresecured by soldering 82 or other suitable means. interposed between eachcontact member 76 and contact carrier 70 and residing in recessestherein is a spring 4.

Attached to the carrier 79 by means of a bracket 85 and screws 86 is alow voltage switch 88 which is similar to the one shown in the firstembodiment of the invention. Also attached to the carrier 7 by means ofpins 90 residing in holes 92 is an actuating lever 94 having oppositclydisposed cams Q6 rigidly attached thereto. An abutment 98 is provided onone portion of the actuating lever 94 which normally engages the buttonMP of the low voltage switch 88.

The operation of the modification shown in Figures 4, and 6 is similarto that shown in Figures 1, 2 and 3 and is as follows:

With the actuating lever 94 in a downward position the cams 96 do notengage the ends of the contact members 76 and the contact tips 78 areheld outward in position to normally engage the stationary contacts 12when the member 14 and the carrier 79 is rotated back and forth.However, when it is desired to disconnect any circuit attached to thestationary contacts 12 and the rotatable portion 14 and still allow therotatable portion 14 to move backward and forward between the stationarycontacts 12, the actuating lever 94 is lifted or rotated upwardly to aposition 180 removed from its normal down position. When the lever 94 isso actuated the cams 96 which are rigidly attached thereto, engage theends of the contact members 76 and push them outward or away from thecontact carrier 76. Such movement of the ends of the contact members 76causes the members 76 to pivot about the pins and the tips 78 to moveinwardly and toward the contact carrier 76 and away from the stationarycontacts 12. Also when the actuating lever is moved to this up positionthe button 106 of the low voltage control switch S8 is released causinga change in the relative connection of circuits attached to the switch83. This will compensate for any changes in the heavy current circuitswhen the contact tips 73 can no longer make contact in the differentrotating positions of the rotative member 14.

It will now be appreciated that unique switch mechanisms have beendescribed which may be used to simultaneously accomplish dual electricalfunctions. They are adapted to prevent completion of one of the maincircuits controlled by a'multiple pole double throw switch withoutinterrupting the other main circuits controlled by such a switch. At thesame time these unique mechanisms provide for automatic actuation ofauxiliary switching means to compensate for any changes that might benecessary in the electrical system controlled by this multiple doublethrow switch due to the cut-out of one circuit.

I claim:

1. An electrical switch including a stationary contact, a movablecontact carrier, contact means pivotally fastened to said carrier, meansto shift said carrier and move said contact means into and out ofengagement with said stationary contact, and cam means includingco-opcrable cam surfaces associated with said contact means and saidcarrier and operable to pivot said contact means on said carrier out ofengagement with said stationary contact when said carrier is in aposition to cause said contact means to engage said stationary contact.

2. An electrical switch including a stationary contact, a rotatablecontact carrier, a movable contact pivotally attached to said carrier,means to rotate said carrier and move said movable contact into and outof engagement with said stationary contact, and means to pivotally movesaid movable contact relative to said carrier out of engagement withsaid stationary contact when said carrier is ina position to cause saidmovable contact to engage said stationary contact including a surface onsaid movable contact removed from the location where saidmovable contactis pivotally attached to said carrier and a cam movably attached to saidcarrier and having a cam surface engageable with said first mentionedsurface.

3. An electrical switch comprising a stationary contact, a rotatablecontact carrier, a movable contact pivotally attached to said carrier,means to rotate said carrier and 'rnove said movable contact into andout of engagement able with said pin which upon being manually actuatedcause said pin and said movable contact to move away from saidstationary contact.

4. An electrical switch comprising a stationary contact, a rotatablecontact carrier, a movable contact pivotally attached to said carrier,means to rotate said carrier and move said movable contact into and outof engagement with said stationary contact, and means to hold saidmovable contact out of engagement with said stationary contact when saidcarrier is in a position that would normally cause said movable contactto engage said stationary contact including a pin attached to saidmovable contact member and located remote from the point of pivotalattachment between said movable contact and said carrier, and arotatable cam attached to said carrier and having cam surfacesengageable with said pin for holding said movable contact removed fromsaid stationary contact.

5. An electrical switch including a pair of oppositely disposedstationary contacts, a rotary contact carrier, a pair of movablecontacts movably attached to said carrier and interposed between saidstationary contacts, means to limitedly rotate said carrier back andforth to cause each of said movable contacts to alternately engage anddisengage with one of said stationary contacts, and manually actuatedcam means to retract said movable contacts to prevent engagement of saidmovable contacts with said stationary contacts when said carrier is solimitedly rotated including carn surfaces associated with each of saidcontact means and a rotatable cam attached to said carrier intermediatesaid surfaces, said cam having surfaces cooperable with said firstmentioned surfaces which upon rotation of said cam move said firstmentioned surfaces relative to said carrier.

6. An electrical switch comprising a pair of oppositely disposedstationary contacts, a rotary contact carrier, a pair of movablecontacts movably supported on said carrier and interposed between saidstationary contacts, means to limitedly rotate said carrier back andforth to cause each of said movable contacts to alternately engage anddisengage with one of said stationary contacts, and means to retractsaid movable contacts to prevent engagement of said movable contactswith said stationary contacts when said carrier is so limitedly rotatedincluding a rotatable cam attached to said carrier and having camsurfaces which when said rotatable cam is actuated are adapted to engagemeans on said movable contacts and cam said movable contacts toward eachother and away from said stationary contacts.

7. An electrical switch including a pair of oppositely disposedstationary contacts, a rotary contact carrier, a pair of movablecontacts movably attached to said carrier and interposed between saidstationary contacts, means to limitedly rotate said carrier back andforth to cause each of said movable contacts to alternately engage anddisengage with one of said stationary contacts, manually operated cammeans to retract said movable contacts to prevent engagement of saidmovable contacts with said stationary contacts when said carrier is solimitedly rotated, and secondary switching means mounted on said carrierand actuated by said manually operated cam means,

8. An electrical switch including a stationary contact, a movablecontact carrier, a movable contact attached to said carrier, means tooperate said carrier to move said movable contact into and out ofengagement with said stationary contact, secondary switching meansmounted on said carrier, and cam means associated with said carrier,said movable contact and said secondary switching means, said cam meansbeing operable to simultaneously move said movable contact out ofengagement with said stationary contact when said carrier is in aposition to cause said movable contact to engage said stationary contactand actuate said secondary switching means.

References Cited in the file of this patent UNITED STATES PATENTS1,276,110 Rasmussen Aug. 20, 1918 1,702,035 Berthold Feb. 12, 19292,059,023 Perry Oct. 27, 1936 2,163,919 Siegel June 27, 1939 2,594,181Kliegl et al. Apr. 22, 1952 FOREIGN PATENTS 200,132 Great Britain July2, 1923

